With a regulator of this type, preferably a cascade regulator, the exhaust gas composition is sensed using the lambda probe arranged upstream or downstream of the catalytic converter and the injection quantity of the fuel supply of the internal combustion engine is correspondingly controlled so that the desired exhaust gas composition can finally be reached again. This ensures that the lambda value lies within a desired range, as a result of which the content of HC, NOX and CO is reduced to a minimum.
The exhaust gas emission values are dependent here on the control speed of the regulating circuit, in particular in the warm-up phase of the internal combustion engine.
With regulating methods having two binary lambda probes, one is arranged upstream of the catalytic converter and the other is arranged downstream of the catalytic converter in the flow direction of the exhaust gas. The voltage of the binary lambda probe upstream of the catalytic converter is converted into an item of binary information, which specifies whether this currently concerns an enriched or a lean exhaust gas concentration. A value is determined on the basis of this item of information, with which value the injected fuel quantity in the fuel supply of the internal combustion engine is controlled. If the lambda probe upstream of the catalytic converter senses a lean exhaust gas composition, the value of the mixture formation is reduced step-by-step from a value of λ=1.0 to a value of 0.98 . . . 0.97, until the lambda probe senses a status of the rich exhaust gas composition. As a result of recognizing the rich exhaust gas composition, the value of the mixture formation is now increased by an increment to λ=1.0 and subsequently step-by-step to 1.02-1.03. The step-by-step increase and/or drop in the lambda value is referred to as an integral component and the abrupt feedback of the lambda value is referred to as a discontinuous component. This cycle is referred to as a so-called lean/rich amplitude, with a rich amplitude being assumed for instance with a lambda value of 0.97 and a lean status being assumed for instance with a lambda value of 1.03, based on a lambda target value of 1.0.
This regulating method is however disadvantageous in that if unexpected changes occur, the enrichment and/or enleanment of the mixture continues after the provided step-by-step increase and/or drop in the lambda value until the exhaust gas probe has redetected a change in the status from lean to rich and/or from rich to lean. The regulating circuit thus responds to changes in a delayed manner.